Grzegorz Różyński

Data-driven modeling of multiple longshore bars and their interactions

Abstract Long-term bathymetric surveys at a coastal segment of the southern Baltic coast were investigated with empirical orthogonal functions (EOF) to determine the characteristic evolution patterns of multiple longshore bars and with canonical correlation analysis (CCA) to evaluate the importance of interactions among them. The investigated beach is located at Lubiatowo on the Polish Coast and is mildly sloping with multiple, usually four bars, and a median grain size of 0.22 mm, being typical for the coast in the southern Baltic Sea. Data on bed topography have been collected at Lubiatowo since 1987, predominantly twice a year, to record changes in the seabed along 27 lines covering a longshore×cross-shore area of 2600 m×1000 m. The EOF analysis revealed three persistent long-term cross-shore patterns accounting for about 2/3 of the overall signal variance and describing key elements of the evolution of multiple bars. Moreover, it detected subsystems of two inner and outer bars. The CCA study demonstrated that more that 60% of the evolution of inner bars can be explained by the variability of outer bars. The two subsystems thus display significant interactions; they can be largely attributed to vertical variations of the whole nearshore zone, expressed through changes in the equilibrium, Dean-type profiles. Such changes can only be produced by large scale phenomena, e.g. sequences of extreme events, affecting the whole nearshore topography. Hence, part of the variability of inner bars not related to the evolution of outer bars should stem from changes occurring during calm periods, when small waves pass over outer bars unaffected. The paper demonstrates usefulness of the CCA method in coastal engineering and a more general strategy of data-driven investigations with more than one method in order to make use of synergy generated with such a complex approach. The benefit of such a synergy is that results from both investigations can be critically intercompared, so more accurate joint interpretations become feasible.

Forced and self-organized shoreline response for a beach in the southern Baltic Sea determined through singular spectrum analysis

Abstract Temporal and spatial variations in shoreline position along the southern Baltic coast were investigated using singular spectrum analysis (SSA) with the overall aim to determine characteristic patterns in the shoreline response and whether these patterns displayed forced or self-organized behavior. The investigated beach is located at Lubiatowo on the Polish Coast and is mildly sloping with multiple bars having a median grain size of 0.22 mm, being typical for the coast in the southern Baltic Sea. Data on coastal morphology have been collected at Lubiatowo including (1) bathymetric surveys since 1987 twice a year to cover changes in the seabed (along 27 lines covering a longshore×cross-shore area of 2600×1000 m), and (2) beach topography surveys since 1983 every 4 weeks on the average, extending from the shoreline to the dune foot (along the same 27 lines). Furthermore, several dedicated field campaigns have been carried out at Lubiatowo, as well as measurements of deep-water wave properties since 1998. SSA was employed to the time series of shoreline position from all 27 survey lines. The analysis method demonstrated a large potential for detecting temporal patterns from fairly short and noisy time series with irregular sampling interval. In summary, three dominant patterns emerged jointly reproducing 70–90% of the overall variation in the data for the different survey lines. These temporal patterns were demonstrated to represent forced and self-organized components describing the variation in shoreline position. The forced components could be related to the mean properties of the wave climate, whereas the self-organized components were mainly influenced by particular events or features of the beach such as storm waves, storm surges, beach type (dune, cliff), and sediment characteristics.

An integrated Pan-European perspective on coastal Lagoons management through a mosaic-DPSIR approach.

A decision support framework for the management of lagoon ecosystems was tested using four European Lagoons: Ria de Aveiro (Portugal), Mar Menor (Spain), Tyligulskyi Liman (Ukraine) and Vistula Lagoon (Poland/Russia). Our aim was to formulate integrated management recommendations for European lagoons. To achieve this we followed a DPSIR (Drivers-Pressures-State Change-Impacts-Responses) approach, with focus on integrating aspects of human wellbeing, welfare and ecosystem sustainability. The most important drivers in each lagoon were identified, based on information gathered from the lagoons’ stakeholders, complemented by scientific knowledge on each lagoon as seen from a land-sea perspective. The DPSIR cycles for each driver were combined into a mosaic-DPSIR conceptual model to examine the interdependency between the multiple and interacting uses of the lagoon. This framework emphasizes the common links, but also the specificities of responses to drivers and the ecosystem services provided. The information collected was used to formulate recommendations for the sustainable management of lagoons within a Pan-European context. Several common management recommendations were proposed, but specificities were also identified. The study synthesizes the present conditions for the management of lagoons, thus analysing and examining the activities that might be developed in different scenarios, scenarios which facilitate ecosystem protection without compromising future generations.

DEPTH OF CLOSURE AND SEABED VARIABILITY PATTERNS

Detailed studies have been undertaken to assist in the design of major extensions to the port of Haifa. Both numerical and physical model studies were done to optimise the mooring conditions vis a vis the harbour approach and entrance layout. The adopted layout deviates from the normal straight approach to the harbour entrance. This layout, together with suitable aids to navigation, was found to be nautically acceptable, and generally better with regard to mooring conditions, on the basis of extensive nautical design studies.Hwa-Lian Harbour is located at the north-eastern coast of Taiwan, where is relatively exposed to the threat of typhoon waves from the Pacific Ocean. In the summer season, harbour resonance caused by typhoon waves which generated at the eastern ocean of the Philippine. In order to obtain a better understanding of the existing problem and find out a feasible solution to improve harbour instability. Typhoon waves measurement, wave characteristics analysis, down-time evaluation for harbour operation, hydraulic model tests are carried out in this program. Under the action of typhoon waves, the wave spectra show that inside the harbors short period energy component has been damped by breakwater, but the long period energy increased by resonance hundred times. The hydraulic model test can reproduce the prototype phenomena successfully. The result of model tests indicate that by constructing a jetty at the harbour entrance or building a short groin at the corner of terminal #25, the long period wave height amplification agitated by typhoon waves can be eliminated about 50%. The width of harbour basin 800m is about one half of wave length in the basin for period 140sec which occurs the maximum wave amplification.Two-stage methodology of shoreline prediction for long coastal segments is presented in the study. About 30-km stretch of seaward coast of the Hel Peninsula was selected for the analysis. In 1st stage the shoreline evolution was assessed ignoring local effects of man-made structures. Those calculations allowed the identification of potentially eroding spots and the explanation of causes of erosion. In 2nd stage a 2-km eroding sub-segment of the Peninsula in the vicinity of existing harbour was thoroughly examined including local man-induced effects. The computations properly reproduced the shoreline evolution along this sub-segment over a long period between 1934 and 1997.In connection with the dredging and reclamation works at the Oresund Link Project between Denmark and Sweden carried out by the Contractor, Oresund Marine Joint Venture (OMJV), an intensive spill monitoring campaign has been performed in order to fulfil the environmental requirements set by the Danish and Swedish Authorities. Spill in this context is defined as the overall amount of suspended sediment originating from dredging and reclamation activities leaving the working zone. The maximum spill limit is set to 5% of the dredged material, which has to be monitored, analysed and calculated within 25% accuracy. Velocity data are measured by means of a broad band ADCP and turbidity data by four OBS probes (output in FTU). The FTUs are converted into sediment content in mg/1 by water samples. The analyses carried out, results in high acceptance levels for the conversion to be implemented as a linear relation which can be forced through the origin. Furthermore analyses verifies that the applied setup with a 4-point turbidity profile is a reasonable approximation to the true turbidity profile. Finally the maximum turbidity is on average located at a distance 30-40% from the seabed.

Field Observation of Edge Waves and Beach Cusps on the South Baltic Sea Coast

Abstract Within the two major theories of the generation of rhythmic shoreline features, the earlier one relates to edge waves, whereas the one developed later perceives shoreline rhythmic forms as effects of self-organized shoreline behavior. This study focused on identification of infragravity waves (edge waves) and periodic components of shoreline configuration and searched for their potential relationships in the mildly sloping, sandy south Baltic coast. The objective was not to suggest which theory better describes shoreline rhythmic features but was chosen for an empirical assessment of possible links between the generation of rhythmic morphological beach forms and specific infragravity waves motion at a dissipative shore. The investigated area features a gently sloping seabed with several bars inducing multiple breakers, which can be classified as a dissipative beach. Field measurements were taken during two periods lasting several months each. Long records of water table oscillations, nearshore currents, and measurements of shoreline configurations were analyzed using various signal processing techniques, incorporating traditional spectral analysis and the modern statistical techniques of singular spectrum analysis and discrete wavelet transform. The measurements revealed two clearly visible infragravity components with periods Tk = 30–40 seconds and Tk = 100–120 seconds at a dissipative south Baltic beach with multiple bars. They were detected by all three methods employed in the study. Additionally, less pronounced components were identified with periods Tk = 180 seconds and Tk = 10–12 seconds. The analysis of variability of the shoreline shape found periodic components with wavelengths ranging between several and several hundred meters and more. Results of this study also suggest that there are links between infragravity waves and rhythmic shoreline forms in a dissipative shore with multiple bars.

Extreme water levels of the Vistula River and Gdansk Harbour

Using Canonical Correlation Analysis (CCA), Rozynski et al. (2006) have demonstrated that there is a weak correlation between the water levels of Vistula River and Gdansk Harbour. Herein the CCA analysis serves as a first step for a univariate bootstrap resampling technique, applied to investigate coincident extreme water levels of Vistula River and Gdansk Harbour. The CCA-derived assumption of statistical independence is argued as being a suitable working approximation for (outline) engineering design. This allows the goodness-of-fit of different statistical models to be assessed in a quantitative manner with a bootstrap method. This also provides a convenient means of defining extreme levels together with their confidence intervals. The analysis with two statistical methods provides insight into the character of joint coastal extremes in an estuary of a large north European river. The rationale and methodology are at least partly applicable to similar estuaries of northern Europe.

Data-Driven and Theoretical Beach Equilibrium Profiles: Implications and Consequences

AbstractThis paper presents a concept of data-driven beach equilibrium profiles of cross-shore seabed records from the coastal station of Instytut Budownictwa Wodnego Polskiej Akademii Nauk at Lubiatowo, Poland, where multiple longshore bars are present. Data-driven equilibrium profiles are the monotonic trends of cross-shore seabed profiles. They were extracted using the empirical mode decomposition method. They retain general properties of Dean profiles, i.e., the Dean coefficients fitted to raw profiles are practically identical to those fitted to their trends. The monotonic property of trends allows for the introduction of cross-shore variable wave-energy dissipation rates, which can be compared with the constant Dean rates. This is the novel element of data-driven beach equilibrium profiles. Variable rates help indicate locations on a beach where wave-energy dissipation is intensive and produces erosion and where it is lower and generates deposition of sediment. In other words, variations of wave-ene...

WIND- AND SEA LEVEL-INDUCED SHORE EVOLUTION IN POLAND

A study of alternatives including a shoreline evolution numerical modelization has been carried out in order to both diagnose the erosion problem at the beaches located between Cambrils Harbour and Pixerota delta (Tarragona, Spain) and select nourishment alternatives.

Coastal Protection and Associated Impacts - Environment Friendly Approach

The paper highlights coastal protection as a component of integrated coastal zone management (ICZM). ICZM particularly emphasizes environmental aspects of all activities in coastal areas, combining research results from natural and social sciences. In this context it particularly favors solutions avoiding undesired disturbances to coastal (eco) systems, including unnatural coastal morphology, poor water quality and impaired biodiversity. Simultaneously, it supports schemes being flexible enough to cope with the global climate change on a longer time perspective. Thus, in the ICZM view, the best measures incorporate soft coastal protection techniques, i.e. artificially initiated natural dunes and beach fills, permeable groins and submerged breakwaters, discussed extensively herein.

Infragravity Waves at a Dissipative Shore with Multiple Bars: Recent Evidence

AbstractThis paper presents more precise evidence on the existence of infragravity waves at a dissipative coastal segment of the Baltic Sea in Poland. The waves were identified with recorded water levels from four gauges in close shoreline proximity, and detailed analyses focused on the output and patterns obtained through the use of discrete wavelet transform (DWT) and cross-correlation functions. As a result, two infragravity waves could be identified: a progressive wave with a period of 34 s, wavelength of 96 m, and a modal number (n = 2); and a standing wave with a period of 130 s, and a wavelength of 252 m, and a modal number (n = 0). The combination of DWT and traditional cross-correlation analysis can serve as a universal tool for nearshore hydrodynamic investigations. Also, this methodology can be applied by extending instrumentation and placing two more wave gauges to form a line of five devices; this potential follow-up research should determine the wavelengths and modal numbers with more precis...